织构几何参数对超疏水钛合金表面润湿性的影响

Effect of Texture Geometric Parameters on Wettability of Superhydrophobic Titanium Alloy Surface

目的研究表面织构几何参数对超疏水钛合金表面润湿性的影响规律。方法利用纳秒激光在钛合金表面构筑不同织构间距、边长和形状的微织构,通过氟硅烷改善钛合金表面的润湿性;借助电子扫描显微镜(SEM)观察钛合金表面织构,利用接触角测量仪表征织构表面接触角;通过多元线性回归方法研究织构参数对钛合金表面润湿性的影响规律。结果氟硅烷改性试样表面静态接触角达到150°,满足超疏水要求,各织构表面滚动角基本稳定在4°~11°,满足疏水要求。当钛合金表面织构间距在0~0.6 mm变化时,织构相对试样表面的占比从80%至20%发生不等变化,随织构占比的减小,织构表面静态接触角明显下降,滚动角呈上升趋势。当织构边长在0~0.6 mm变化时,液滴在不同织构图案上的接触角变化并不一致,正方形钛合金表面接触角从164.6°增加到170°,而圆形、三角形钛合金表面接触角减小,分别从166.9°降低到162.1°、从169.6°降低到160.2°,滚动角呈先增后减的趋势。结论织构几何参数变化对试样表面润湿性有显著影响。织构间距不同会改变织构占比,织构图案几何特征的不同会影响表面润湿性,并且表面润湿性随织构面积的改变而显著变化。通过研究典型织构几何参数对表面润湿性的影响有利于进一步深入理解织构特征对表面润湿性的影响,为未来设计具有多元功能化的表面结构具有重要意义。

Laser etching and fluorosilane modification were used to study the effect of different surface morphology and texture parameters on the wettability of superhydrophobic titanium alloy surfaces.Nanosecond laser was used to construct microstructures with different parameters on the surface of titanium alloy,and the realization of superhydrophobic properties on the surface of titanium alloy was treated by fluorosilane modification.There were many different instruments used to characterize and determine whether the preparation was successful.For example,an EDS analyzer was used to characterize the element types of the prepared superhydrophobic surface.The microstructure of the prepared titanium alloy surface morphology was observed by SEM.In addition,the spreading of droplets on the textured surface was visually observed through an optical contact angle measuring instrument.The change of surface texture parameters affecting the wettability of the superhydrophobic titanium alloy surface were analyzed from two perspectives.On the one hand,the reason for the effect on the wettability of titanium alloy surfaces was analyzed from the different geometric parameters(e.g.,texture spacing,side length,and surface morphology);On the other hand,the synergistic influence degree of multiple texture variables on wettability was quantitatively analyzed by multiple linear regression analysis.The experimental phenomenon could be fully explained by analyzing from these two perspectives.According to the experimental results,no matter how the surface texture parameters changed,the contact angle on them were always greater than 150°,indicating that the change of texture parameters was conducive to the surface being superhydrophobic.And the rolling angle of each texture surface was basically stable between 4°and 11°,meeting the hydrophobic requirements.A 10μL droplet fallen on the textured surface,and the contact angle decreased by a maximum of 10%when the texture distance changed from 0-0.6 mm at the situation of controlling a single variable for analysis.At the same time,the contact angle showed different trends when the texture spacing changed with different texture shapes.To be more detail,when the texture side lengths corresponding to different morphologies varied from 0 to 0.6 mm,the maximum contact angle corresponding to square morphologies was 170°,the minimum value was 167.3°,and the average value was 164.6°;The maximum contact angle of the triangular morphology was 169.6°,the minimum value was 160.2°,and the average value was 165.05°;The maximum contact angle of circular morphology was 166.9°,the minimum value was 162.1°,and the average value was 164.5°.In addition,multiple linear regression analysis of multiple independent variables on the dependent variable was performed to try to establish a mathematical model.According to the test results,these data met the regression conditions of linearity,independence,normality,and non-collinearity.The goodness of fit was 54.5%,which quantitatively illustrated that these independent variables could have a synergistic effect on each other.In summary,according to the experimental results observed,the mechanism behind it is analyzed from the micro perspective of the Cassie-Baxter physical model and surface tension exhibited by droplets on titanium alloy surfaces.The different surface texture parameters that including texture spacing,texture side length,and surface morphology could change the surface superhydrophobic wettability.The distance between textures changes the proportion of textures and affects surface wettability.The different geometric characteristics of texture patterns affect wettability.Square texture improves droplet stability,circular texture increases the surface curvature radius of droplets,reduces surface tension,enhances wettability,and triangular"wedge"areas lead to droplet instability.Furthermore,the surface wettability significantly changes with the change of texture area.Moreover,the linear regression quantifies that there is a synergistic effect between the various factors.By controlling and coordinating various factors through laser etching,the surface wettability can be adjusted more accurately.